Improvement in safety-valves for steam-generators



N. PETERS. PHGTO-LITHOGHAPMER, WASHINGTDN D C 'ilniid giedre gaat cum,

FERDINAND ROCHOW, NEW YORK, N.Y.

. Letters Patent No. 95,382, (lated lSqJtcmbcr 28', 1869.

IMPROVEMENT IN SAFETY-VALVES FOR STEAM-GENERATORS.

The Schedule referred to in these Letters Patent: and making part of thesame.

To all whom it may concern f Be it known that I, FERDINAND RocHow, ofthe city, county, and State of New York, have invented an ImprovedSafety-Valve for Steam-Generators; and I do hereby declare that thefollowing is a full, clear, and exact description thereof, which willenable those skilled inthe art to make and use the same, reference beinghad to the accompanying drawings, in which-v Figure 1 represent-savertical section through the centre of the valve, and the several partsconnected, therewith. l

Figure 2 represents av plan or top view of a part of theenclosing-chest, showing the manner of attaching the lever It to theouter chest. l

Figure 3 represents a vertical section of the .valve-v box, with thevalve and inner cap in elevation, in which is also shown a section ofthe upper part of a .stcain-generatorand steam dome,1to illustratetheapplication of the safety-valve.

In the accompanying drawings- A represents the valve-box, which consistsof two concentric shells.

rlhe outer one, A, forms the valve-seat, and is fitted solid into aflange, M, which is bolted yto the boiler or to the steam-pipe. y

The inner one, A1, forms a hollow cylinder, which is either made toreach directly into the steam-room of the boiler, as shown in the dottedlines A2, or which, where this is not practicable, is closed. by a disk,B, screwed into or bolted to it, and connected by a' small separatepipe, O, with the interior of the steam-room of the boiler.

` Both these shells are connected together by a su'icient number of ribsC C. The outer cylinder A extends above the inner one,

and is so much greater in diameter than the inner one,

.las to leave an open passage, O, between them, as large .,as the areaofthe opening in the valve-seat, and through this passage the steamescapes, as indicated by the arrows, when the valve lifts off its seat.

'lhe valve is formed'cylindn'cal at its lower part D, where it is turnedofI" and furnished with a'sleeve, E, which is bolted tightly to it fromunderneath, through an annular hoiizontalange, by bolts a. This sleeve.is fitted so as to work easily in the cylindrical part A1 of thevalve-box, so that this part of the valve acts like a piston within theinner cylinder A1. A

The connecting-neck D-of the valve is of diminished diameter, and madesemi-spherical, so as to present the least possible resistance to thedow of the escaping steam; and is also furnished with three or fourwings b b, by which the valve is guided in its seatand case. i

The valve D is kept on its seat by the pressure of the spring G actingon the Washer H', nuts J J, and stem K.

The spring is heid in 4irs place by a cap, L, the 1anter being screwedsolid on to the valve-box A by an the cap, near the valveseat, to allowthe steam to escape freely beneath the cap L. v

The stem K is guided at its upper end by the downward-projecting boss l,cast within the cap L, being bored out suiciently deep to allow the stemK to rise the desired height therein.

The washer H fits loosely on the stem K, and a feather, c, fastened intothe washer, works in a corresponding groove in the stern, so that thestem cannot turn in the washer, while the lower end of said stem passesinto a central opening'in thevalve, and is fitted y into a socket in theclosed bottom of said valve.

'lhe operation of this valve is as-follows:

As long as the valve closes tight' on' its seat, the steam from theboiler will exert on it the following pressures:

First, in the upper part of the cylinder A1, (which cylinder -is ofgreater diameter than the opening in the valve-seat,) a downwardpressure, due to the difference between the area of cylinder A l and oftheopening in the valve-seat.

Second, in the lower part of the cylinder A1, an upward pressure, due tothe full area of the cylinder A1. The difference of both, which issimply a pressuredue to the area of the opening in the valveseat, is,therefore, the total pressure on the valve, as long as it is on itsseat. When the valve just commences to raise, the pressure of thespring, and of the steam on the valve, are just on anequilibrium.Practically, the spring is adjusted to exert the proper pressure on thevalve, by screwing up the nuts VJ J so much that the valve will justcommence lifting when the pressure in the boiler, which-is indicated bya steam-gauge, has reached its intended limit.

When the valve commences to liften its seat, and steamto blow on, thesteam-pressure inthe upper part of Acylinder A1 will gradually diminishas the steam escapes more rapidly. There will also be a greater pressureagainst the arch d2, in the upward4 direction,

against which the escaping steam strikes, than againstn total increaseof pressure of steam against the valve,-

in an upward direction from the point whenthe valve commenced to rise,as the pressure in the-lower part of the cylinder A1 is from that pointconstantly the same, whatever distance the valve may lift off its seat,viz, the pressure inside of the steam-boiler, itV not being, affected bythe flow of the escaping steam.

The above-described increasing surplus of 4pressure in lifting thevalve, has therefore to overcome the increased tension of the spring.But this surplus of pressure can be increased by giving the cylinder' A1the proper diameter, because the additional annular area thus added tothe cylinder A1 and piston D by means of the sleeve E, is always actedupon with the full boiler-pressure from below, while the pressure on topof it is decreasing with the rapidity of the escaping steam, or with thedistance which the valve rises from its seat. i 4

Vhen the valve has been raised so high that the escaping steam hasreached its maximum speed (which ought to be the height of lift of aperfect safety-valve) in the upper part of the inner cylinder A1, thenthe action of the steam in this part would remain unaltered on thevalve, whether. it raised more cr not, and if there were any surplus ofupward pressure left, the valve would not commence to come down on itsseat again before there had blown offso much pressure in the boiler,that this surplus of pressure were reduced to nothing.

Thus, by giving the diameters of the inner cylinder A1, and the openingin the valve-seat of the outer cylinder A, the proper proportion, thevalve lmay, first, be enabled to raise the required height, even againstthe increasing tension of a spring, relieving the boiler of an Vunduepressure in the shortest possible time; and, second, it may be enabledto keep open until the pressure of the boiler has fallen Vany desiredamount below the pressure at which it commenced to raise.

A cylindrical lock-up chest, I), is screwed on to the right-augledflange M, in such manner that an inner rim, p, bears hard on to thevalve-box A, and securely holds it in its place. This lock-up casecovers the whole mechanism, and is furnished with a nozzle, Q, for theescape of the steam, opposite to which there is a partition, d, in theinterior, cast across the opening, so that no meddling with the valve ispossible through this nozzle.

There is, further, an opening in the lock-up case left between two eyeseve, cast on the outside of the chest P, and the latter is fitted with ascrew-thread, so that when it is screwed down hard upon the fiange M,this opening is opposite one of the connecting-legs f on the cap L.

A forked lever, R, by which the valve may be raised from outside, inorder to blow off steam, reaches through this opening into the chest,under the washer H, on each side of the nuts J J, the connecting-leg j'being made narrow enough to allow the fork of the lever 1t to embraceit.

A bolt, S, passing through the eyes e e and the lever R, makes itsfulcrum, and connects it to the chest 1?, while a lip, h, is cast on theinside of the chest, under this lever, to support it and prevent itsmoving downward and bearing on the valve.

The cap L is screwed on to the valve-box Awth a left hand thread, V, andthe chest I on to the flange M with right-hand 0r reverse thread W, sothat when the lever It is secured in its place, it is impossible tonnscrew the chest P, as an effort to do so would cause the lever fittingover the leg f to screw the cap L harder on to the valve-box A, and thusthe outer case and the inner cap are completely locked together.

An eye-splint, i, is put through the end of the bolt S, which extendsoutside of the eye c, and a lock put into the eye of this splint, so asto prevent the bolt from being withdrawn.

The application of the safety-valve to a boiler is represented in lig. 3of the drawings, and it will be secu that a steam-pipe extends from thevalve-box into the steam-dome. i

To this steam-pipe, I prefer to attach an umbrellalike shield or disk,somewhat below the opening in the dome, for the escape of the steam, soas to break or interrupt anycurrent of water which may be drawn up bythe force of the escaping steam, when this should blow off too suddenly,and cause the water to fall back again into thc boiler. The arrows inthis figure show the direction of the escaping steam when the valvelifts.

The sleeve E is necessary whenever the cylinder A1 is larger than theopening in the valve-seat, be-

canse, if the piston-part Dlof the valve were simply made larger,thevalve could ,not be got in, as it has to be putin from the top,through the opening in the seat, and the sleeve E afterward screwed toit from below. By making the sleeve E larger or smaller, any surplus ofpressure can be obtained, as above described.

I have found that a valve may be' set to blow off, say at fifty poundspressure, and that this pressure` can be increased to one hundred poundsbefore the valve will open as wide as it ought, the pressure under thevalve being only fifty pounds when it is raised so much o its seat. Ican proportion my valve so as to raise enough to give the whole area ofthe openings through all the passages, maintaining no higher pressurethan as much as 'when it is started' to blow off'.

This safety-valve may also be weighted by a lever and weight, asrepresented in fig. 4. In this case the sleeve E is not necessary, asthe weight does not iucrease with the height the lever lifts. Thecylinder A1 need not, in this case, be made larger than the opening inthe valve-seat, the sleeve E, by'which the increased diamctcr of thevalve is effected, being only a necessity in combination with aspring-weighted valve. When the valve, therefore, is weighted by aspring, the removable sleeve is necessary, to increase the diameter ofthe valve.

Figure 4 shows the application of my invention to a safety-valveweighted by a lever, the valve-box A being airauged exactly as in fig.l, with the pistonpart D of valve I) rather smaller than the opening inthe valve-seat, at least, not larger, so that there is no sleeve Erequired to put in from below.

The lever U is hung in a hinge, T, cast on the box A, and it has'sufficient upward movement to allow the valve to raise its intendedheight, as seen atl the dotted lines a n.

Figure 5 is a modification of fig. 1. Although the piston-part Dl ofvalve D is larger than the opening in the valve-seat, the disk B is doneaway with by the arrangement ofthe separate opening A2, which forms thevalve-seat proper, and which is secured on box A by the cap L, whenscrewed down hard. In this, the valve D2 and piston-partD have to bemade in two separate pieces, and the annular valve is 'screwed to theneck l) after the seat A2 is placed over the valve, as shown in dottedlines', or the piston-part Dl has to be made small enough'to slipthrough the valve-seat, and a sleeve secured to it afterward, analogousto sleeve E. By this modification, the valve may be readily withdrawnby. simply nnscrewing the ea'p L.

Having described my invention,

I claim-l- 1. A valve-box of a safety-valve, having an interiorcylinder, A1, which is, at its upper end, in direct and unobstructedcommunication with the opening in the valve-seat D2, and, at its lowerend, in permanent free communication with the interior of the boileronly, while the escape-opening, with which its upper end communicates,is also in free and unobstructed coin-y munication with the interior oftheboiler, when the valve is made to form a piston, closed at its lowerend, constructed and arranged substantially as before 'described.

2. The combination of the annular sleeve E with the cylindrical portionDl of the valve, and the inner cylinder A1 of the .valve-box,substantially as before described.

3. The inner cap L, constructed with a left-hand screw-thread, V, andthe enclosing-chest P with a right-.hand screw-thread, W, in combinationwith the forked lever R, whereby the said cap and chest are securelylockedtogether, substantiallyas before described.

4. The inner enclosingcap L, constructed with legs f f, and an annularscrew-ring, L2, in combination with the lever R, constructed so as toembrace one ofthe said legs, thus constituting the lock, substantiallyas before described.

5. The inner cap L, for enclosing the spring Gi, and' the outer chest P,for enclosing said cap, constructed and arranged substantially as beforedescribed.

6. The inner cap L, for enclosing the spring G, constructed with acylindrical hollow guide, l, projecting within the spring, so as to forma; guide for the spindle K, substantially as before described.

7 The guard d, arranged above the bottom of the' cap L, and withreference to the exterior of said cap, and the escape-pipe Q, so that,in connection with thc cap, a double protection is afforded to theadjustingdevices of the spring, substantially as before described.

8. The construction and arrangement of the chest P, forked lever R, boltS, eye-splint fi, and flange M,

with the cap L, valve-box A, and valve D, constructed and arrangedsubstantially as before described.

FERDINAND ROOHOW.

Witnesses:

ADoLrLnvINGnn, H. HEYMANN.

